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Re: [Public WebGL] WEBGL_texture_from_depth_video extension proposal



On Mon, Nov 10, 2014 at 8:16 PM, Jeff Gilbert <jgilbert@mozilla.com> wrote:
> Are there a large number of devices which support 16-bit depth sensing but do not support a depth_texture equivalent extension? depth_texture has overwhelming support everywhere but older Android. Any GLES3 device would have it, though.

Uploading a depth camera's output to an OpenGL depth texture won't
work. The only thing an OpenGL depth texture can be used for is a
depth comparison with other geometry in the scene. The GLSL ES 3.00.4
spec section 8.8 says "If a non-shadow texture call is made to a
sampler that represents a depth texture with depth comparisons turned
on, then results are undefined." The application will always have to
perform some post-processing of the depth camera's output, so it has
to be uploaded into a non-depth texture.


On Mon, Nov 10, 2014 at 10:59 PM, Florian Bösch <pyalot@gmail.com> wrote:
> For these reasons, what's likely going to happen with these depth values in
> practical use, is this:
>
> upload the depth to 5-6-5
> decode the depth to some interpolatable format
> use the depth data
>
> It'd a rare usecase indeed that somebody would want to directly work with
> the data as-is.

I think that's overstating the case. Sampling with NEAREST filtering
will probably work fine for a significant class of applications.

The application can render the 5_6_5 texture into an FBO with another
format if it wants to do a GPU-GPU conversion. I think it is not a
good idea to put this code into the browser because:

 - The browser will be responsible for a plethora of format conversions
 - All of these conversions will have to be tested
 - Any bugs in them will have to be worked around by the application anyway
 - They can be implemented with the same efficiency, portably, by the
application in JavaScript, using WebGL


On Tue, Nov 11, 2014 at 5:21 AM, Mark Callow <khronos@callow.im> wrote:
> Capturing depth video into a texture has basically the same needs as capturing regular video. So this extension and WEBGL_dynamic_texture should be developed together. The synchronisation features will be needed by both types of data.
>
> The Media Capture Stream must be something fairly recent as I don’t recall seeing it when I was writing WDT but it clearly should be one of the sources that can be used with dynamic textures.

Let's certainly move WEBGL_dynamic_texture forward. These two
extensions don't need to gate each other.

-Ken

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